An order of 0 corresponds to convolution with a Gaussian
kernel. An order of 1, 2, or 3 corresponds to convolution with
the first, second or third derivatives of a Gaussian. Higher
order derivatives are not implemented

output : array, optional

The output parameter passes an array in which to store the
filter output.

mode : {‘reflect’, ‘constant’, ‘nearest’, ‘mirror’, ‘wrap’}, optional

The mode parameter determines how the array borders are
handled, where cval is the value when mode is equal to
‘constant’. Default is ‘reflect’

cval : scalar, optional

Value to fill past edges of input if mode is ‘constant’. Default
is 0.0